Posts Tagged ‘Urocyon cinereoargenteus’

It’s no secret that I have a bit of infatuation the canids in the genus Urocyon. Not only are they considered the most basal form of extant canid, it is very likely that there are multiple cryptic species in the genus that need more molecular and morphological investigations to ascertain.

These canids are unique among North American dogs in that they are great tree climbers. Indeed, they are the most arboreal of all dogs. While the raccoon dogs of the Old World certainly do climb with their long hooked claws, the gray foxes take to the trees as readily as cats do.

A few years ago, I came across these images of some Southwestern gray foxes climbing in trees that were adorned with skeletons. I initially thought they had been placed in these trees to attract the foxes to the trail camera, and I pretty much ignored them.

The most unusual photo from the series shows a gray fox standing on a branch where it has placed a dead collared peccary (javelina) “piglet.” The adults of this species are so much larger and so much more aggressive than any gray fox, and I cannot help but wonder how the gray fox managed to catch such a trophy. It had to have taken some guts if the fox caught it on the run, but the researcher who got these photos claims that the foxes do trail peccaries in hopes of snatching a little one.

Lots of research goes into wolves and coyotes. They are the charismatic canids of North America, and both North American and Old World red foxes have also been extensively studied.

But gray foxes don’t get that same billing, and that is pretty sad. They are not like the short-eared dog of South America, where they intentionally live as far from human settlements as possible and are quite difficult to study. Gray foxes are pretty common in North America, if you live south of Canada and outside of the Northern Rockies and the Northern Great Plains of the United States.

I think the name has something to do with it. The name “gray fox” has a connotation with something drab and bland, while “red fox” has a spicier feel.

One implication of the recent finding of the potential existence of two species of gray fox on the North America mainland is that the proposed Western species might derive from an Irvingintonian Urocyon that is not ancestral to the proposed Eastern species.

This analysis was derived from a limited mitochondrial DNA analysis and should be taken with a grain of salt, but it seems likely that at least two species really do exist on this continent. More work from the full genome needs to be performed, and my guess is this research is currently being performed. The article might be out in peer-review right now, and one day, we’ll know for sure.

But there is something mysterious about these little canids. They are move like little cat-dogs, and in the Southwest, at least, they are little dog-leopards, caching their prey in trees where the coyotes can’t go.

The more we know about these lesser dogs, the more they intrigue me. Indeed, the whole lesser parts of Carnivora have me a bit enthralled. The tiger is largely known, as is the wolf, but the mysteries lie with the Eastern spotted skunk in the High Alleghenies of West Virginia, with the long-tailed weasels of canyon lands of New Mexico, and with the bat-eared foxes of the Kalahari.

So now, we must consider the meek and the mild and drab. We must now come to know them, to let their mysteries be revealed in all their glory. We will be shocked, I’m sure

Like this:

A few weeks ago, we lost at least two canid species. Analysis of whole genome sequences indicated that the red and Eastern wolves are recent hybrids between wolves and coyotes. Indeed, this study also showed that the genetic variance between coyotes and wolves is equivalent to the variance between wolf populations, which actually calls into question whether coyotes are a valid species as well.

But this finding does not mean that there aren’t new cryptic species to be found in North America’s endemic canids.

I was just perusing some of the literature on gray foxes, when I came across this study in PLOS ONE. The authors sequenced mitochondrial DNA from 169 gray foxes from California and Georgia, as well as 11 “island foxes” and added in a sample from an aberrant gray fox that wound up in Washington State.

The authors were trying to figure out if California and the American Southeast represented a kind of “glacial refugia” for the species during the Last Glacial Maximum.

What they found was a deep divide between Eastern and Western populations. The California and Washington samples and those from the “island foxes” were estimated to have separated from the Georgia samples some 500,000 years ago. That’s actually greater than current genetic distance between Old World and North American red foxes, which separated 400,000 years ago, and are currently being proposed as distinct species.

We know from previous studies on Eastern gray fox mitochondrial DNA studies that the gray foxes of the Northeast are relatively recent colonizers from the Southeast. So my guess is that we’d find a similar divergence between gray foxes from New York and Ohio and those from California as was seen in this study with Georgia and Western gray fox samples.

Now, this study looked at only mitochondrial DNA, and this is only a tiny part of the genome. More detailed genetic studies are needed to determine the exact time of divergence between the two gray fox populations. Further, because this study included foxes from only California, Washington, and Georgia, it doesn’t really show us where the divide between these two lineages exists on the North American continent. More samples from across the range of gray foxes could give us that answer. My guess is there is a hybrid zone between the two lineages either in the Southwest or in the South-Central US.

But this assumes that there really this genetic divergence is confirmed with nuclear DNA sampling. It could be that the Western population just has an old mitochondrial DNA sequence that wound up surviving, even though the majority of the gray fox genome comes from same source as the Eastern gray fox.

It could be, but there is still a very strong possibility that Western gray foxes do represent a distinct species from the Eastern gray fox, and this question can be answered. We just need analysis from a bigger part of the genome from a broader cross section of gray foxes.

If there actually is a distinct species of Western gray fox, then it would be obvious that the island foxes, which have only been on the Channel Islands for 7,100-9,200 years, should be classified as part of that species. The authors found that no extant population of gray fox in California actually gave rise to the island fox, but there are similarities between island foxes and those in Northern California. But they were still part of this Western gray fox division.

I’ve thought it very odd that gray foxes live in Minnesota quite well, but in the West, they don’t come as far north as western Oregon. The Washington sample in this study was the first gray fox found north of the Columbia River, and western Washington has a much, much milder climate than Minnesota.

Maybe the differences in range reflect a difference between species. Maybe the gray fox of Minnesota is the same as the gray fox of Georgia, and this species has evolved more cold tolerance than the Western species.

There are just so many questions that arise from one study that has largely been overlooked.

And if there are two species of gray fox on the North American mainland, there could be several cryptic species of gray fox in Mexico and Central America. Maybe the isolated populations of gray fox in Colombia and Venezuela are also different species.

The Urocyon foxes are really interesting animals. They are the most basal of all canids, and among North American canids, they are the only one without any connection to Eurasia.

Most taxonomists divide the genus into two species: the gray fox and the island fox. The island fox was recently removed from the Endangered Species List, but I’ve always been very doubtful that it actually is a species. Most of the evidence now shows that it was actually introduced by people. Something very similar could happen with red foxes in Australia, which are now reproductively isolated from the rest of the Old World red foxes. Maybe in 9,000, they will be morphologically distinct enough for someone to declare them the “Australian fox” and work to preserve them as a distinct species.

But in focusing so much on this odd insular population, could we have missed the really big story about the urocyon? Maybe there were two species after all, but we never bothered to look into it.

Maybe one day, we’ll have Urocyon cinereoargenteus and Urocyon occidentalis as the two species of gray fox native to the United States.

Like this:

The sun sets on a muggy July day in northern West Virginia. As darkness envelops the land, the stidulations of crickets and other buzzing insects replace the last of the birdsong. The last rays of the sun cast shadows on an old hayfield, leaving a hazy glow among the grass just now growing back green from the first cutting.

White-tailed deer wander into the hayfield with caution. Months before, the bullets flew through the air at them, and though those days are long way off, the deer do not forget the lesson of November. In the open, man and his bullets can drop the deer at many yards. In the forest, there is security, but sweet clover grows in the rowen. And for that repast, they will risk exposure.

But they will not enter with out their noses and ears and eyes trained into the distance. Every once in a while, a deer jerks its head up and rotates its ears at some sound. It might only be the scurrying of a mouse or vole, but it might be a spotlighting deer poacher pushing the safety forward on his rifle.

It takes only one mistake, so each sound is taken seriously.

But as the darkness draws, the deer begin to relax a bit. The clover is good and fresh and cool.

As the deer graze the clover, a gray form materializes on the opposite side of they hayfield. It is cat-like in its movements, but it sniffs the ground with purpose, like a beagle tracking a cottontail through the edge of a brier patch.

It is the form of a little gray fox, a creature that lies somewhere between the foxes we all know so well and the primitive raccoon-like dogs from which all dogs descend. The gray fox’s kind first appeared during the Pliocene and evolved to live in humid forests much like the one that surrounds the hayfield on all sides.

During the day, the fox seeks the same shelter in the forest that the deer seek. For generations, the hunters have shot the foxes for their fur and to protect their stupid chickens, which foolishly roost in trees where a fox can easily climb up and catch them.

This fox is not a chicken poacher. She never even seen one. Her whole life’s work is the pursuit of the vole and the mouse and the dashing run at the cottontail. In the spring, she robbed a few turkey nests and climbed into the trees to rob the nests of robins and thrushes and warblers.

Tonight she has come to check out some vole trails that ravel along an old access road and end in a hedgerow of autumn olive where she came across a rabbit nest a few weeks earlier.

A fox in her second year should have a growing litter of kits to feed, but this fox’s litter all died when her mate was killed running across a road where he was certain there would be no traffic. With no mate to bring her fresh meat during the nesting season, her milk dried up and hunger forced her to abandon the den.

She has been a lone fox all these months and only now is she coming back into her fine form. Her summer pelt is thick and platinum silver trimmed in an elegant tawny red behind her ears and on her legs and under belly. Down her tail runs a strip of black hair, which she an raise as a hackle whenever she is enraged or nervous.

But there is none of that now. Her nose is quivering at the scent of meadow voles. One has just run down this little trial. The fox lifts her nose to see if she can catch its scent in the air.

A tiny bit of vole scent wafts into her right nostril. She turns to the right, cautiously stepping into stalk. The vole becomes nervous and scurries a bit. The fox’s ears catch the sound, and she stops. She cocks her head to catch the sound a little more clearly. The vole scurries again, and, in its confusion moves, into a copse of grass just two yards from the fox.

The fox inches closer to the copse. The vole remains still. The fox cocks her head again. Her black nose quivers to catch the vole scent again. She knows that in that copse of orchard grass there is a nice fat vole, and now she must prepare to make her leap.

She digs into the ground, and one can almost hear her counting off before she bounds forward into the vole’s poorly-chosen refuge. Her jaws hit the grass with just precision that vole almost explodes into them as she draws down upon her quarry.

She raises her head from the grass as a squeaking vole screams out in its death throes in her mouth.

One vole down. One more bit of protein to hold over starvation.

The deer raise their heads and stamp and blow warning bark-wheezes at the sound. They know the sound of successful predation. In the spring, the coyotes and bears had lifted some their fawns in much the same manner, and the bawling fawns were unable to be saved as the forest monsters carried them off to their deaths.

A squeaking mouse unnerves them in much the same way.

The fox becomes unnerved by the agitated deer, but she soon dispatches the vole and chokes him down. All that noise might be attracting a deer, but they could just as a easily drawn in a coyote or another fox.

And she is more than content to have this hayfield to herself. Last week, she’d run out a young dog red fox who thought he could chase rabbits here all night long. She set the record straight with a few well-timed bites on the backside.

But this little gray fox is not the empress of the hayfield. At any moment, a coyote could show up and run her off. An enterprising predator hunter could take a few shots at her. Dogs could come running after her for nothing more than a good chase. A great horned owl could come sailing silently from the sky and carry her off.

Her life is harrowing yet perfect. Fields of voles and mice and rabbits will feed her well. Feral apples and pears will give her a little desert.

And though her kind must face danger in order to survive, there has been no time in the gray fox’s evolutionary history when times were so good. The death of the agrarian economy in West Virginia has meant more old fields and more reforestation. The gray fox is a creature of the forest, and when this land was heavily forested before, it was forced to share it with any number of larger predators, including cougars and wolves.

And with fur prices not being worth the trouble for all but the most devout predator hunter and trappers, there really aren’t that many people out to get her.

She may not be the empress, but in this moment is she is certainly regal. She is a predator that has just successfully caught her prey. The ancient call of predators to seek their prey has driven evolution in truly profound ways, yet its successful sequence is both brutal and spectacular. It’s not quite the same as watching a pride of lions take down a Cape buffalo.

But it is essence, it is the same thing.

With the vole now thoroughly swallowed, the fox stops to drink from the muddy ditch that runs alongside the access road. A northern green frog leaps out as the fox approaches. She offers to give chase but gives up as soon as the frog buries itself in the mud at the bottom of the ditch.

The fox drinks the water and then caster her nose into the wind. She quivers her nose to catch the scent of any quarry or predators or competitors that might be nearby. Her nose registers nothing.

She trots down the access road then dives down into the treeline. She crosses an unnoticeable trail that goes through a patch of multiflora roase and then turns to take it deep into the woods where dogs and man never go.

And thus the meadow fox leaves the hayfield and whatever drama she brought to it.

The deer continue their clover supper, and the crickets carry on with their night song.

After spending two winters in a row in the deep freeze, it looks like this one is going be one of those depressing, gray ones. It also makes it easier for me to imagine the real effects of climate change, even though the global climate was definitely changing when we were having -20 degree nights last year.

One of the real effects of climate change is that the ranges of animals are changing. Those native to cold climates are pushed deeper into arctic and subarctic climates, while those from more southerly climes work their way north.

The gray fox is very common in the United States. If you live east of the Great Plains and near some woods, you’re likely not far from a gray fox. We take the animal almost for granted.

The gray fox does range into Canada, but it’s generally found only near the US border. As far as I know, the only breeding population that has ever existed in Canada is in Southern Ontario into Southwestern Quebec, and currently, the only listed breeding population is on Pelee Island, which is between Detroit and Cleveland on Lake Erie.

Climate change means that winters are getting milder, on average, and this means that Eastern Canada is likely to experience an upward growth of gray fox populations as time goes on. I think this a fair trade. The red foxes we have in the Eastern US migrated from Eastern Canada as the forests were cleared, and as the climate warms, our gray fox will become part of its native fauna.

In 2008, the potential of the gray fox becoming more established in Canada was realized when a gray fox was caught in a beaver trap in Charlotte County, New Brunswick. This gray fox was well north of its breeding range. The nearest breeding population is just east of Bangor, Maine, so this fox was a long way from home. The fox had traveled something like 84 miles, which is pretty long distance for an animal that is usually a bit smaller than a pug. The young dog foxes of this species do occasionally make wide dispersals from their parents’ territories, and this one made a big run from his mother’s den. He was a subadult, just lighting out for the territories.

The stomach revealed the last meal of the fox– a ruffed grouse. Parasites in his small intestine revealed that he’d been living on snowshoe hares, probably his entire short life.

The authors who explored the New Brunswick gray fox case examined the historical distribution of the species. We have archaeological records of gray foxes from Manitoba, Ontario, and at least Cumberland County Maine, but 350 years ago, the population crashed in Canada. It also crashed in the Great Lakes region of the US, northern New York, and Northern New England. Then in the period from 1930 to 1940, it began to recolonize much of northern New England and the Great Lakes states. They do occasionally wander into Quebec, Ontario, and extreme southern Manitoba.

But with a warming climate, it looks like the gray fox is moving north, and it is very likely that breeding populations will be found deeper into Canada.

No one had ever heard of a gray fox in New Brunswick, but it may not be long before they really do become established well outside of their historic range.

I once read that the main thing keeping them from spreading north was they were too reliant upon cottontail rabbits as a prey source, but apparently their numbers have only increased in Maine as the rabbit population has crashed. Maine, like most of northern New England, is becoming more and more forested, and those forests are maturing. Cottontail rabbits don’t like that particular habitat, and what’s more, Eastern cottontails aren’t actually native to Maine. They were introduced for sporting purposes, and they thrived in the land of small farms.

Gray foxes prefer forested habitat, and they have spread well outside the range of cottontail rabbits in Maine. The remains of the dear New Brunswick fox revealed that the gray foxes of Maine were living well on snowshoe hares and ruffed grouse. They simply don’t need cottontails to thrive.

If gray foxes do become more established in Canada, it will be interesting to see what kind of foxes actually do evolve to adapt to that part of the world. Will they be bigger (in keeping with Bergmann’s rule)? Will they grow thicker coats?